Method for burning liquid fuel



Nov. 5, 1935. H. A BOST METHOD FOR BURNING LIQUID FUEL 3 Sheets-Sheet 1Filed Feb. 24, 1930 Nov. '5, 1935. 505

METHOD FOR BURNING LIQUID FUEL Filed Feb. 24, 1930 3 SheetsSheet 2 4 IINVENTQR I /7 BY I ATTO RN EY Nov. 5, 1935. H. A. BOST METHOD FORBURNING LIQUID FUEL Filed Feb. 24, 1930 3 Sheets-Sheet 3 Patented Nov.5, 1935 PATENT OFFICE METHOD FOR BURNING LIQUID FUEL Henry A. Bost,Euclid, Ohio, assignor to The Otis Steel Company, Cleveland, Ohio, acorpo- V ration of Ohio Application February 24, 1930, Serial No.430,703

3 Claims. (01. 158-1175) This invention relates to a method for.effectively cheapening the cost of using fuels and increasing theefficiency thereof, permitting the use of crude or low grade oils inopen hearth steel 5 furnaces and the like.

In order to obtain efficient combustion of low grade or cheap oils it isnecessary first to vaporize them completely. Heretofore the practice hasbeen to atomize oil or tar with air underpressure sufficient to spraythe oil into the combustion chamber of a furnace ,v where the radiantheat of the furnace raised the temperature of the mixture to vaporizethe oil. This method has proven unsatisfactory in that completevaporiza- .tion has not beenobtained, and consequently combustion hasbeen ineificient. The large V01- ume of relatively cool air necessarilyintroduced into the furnace tends to reduce the temperature therein.Likewise, vaporization is retarded, due to the fact that the oilglobulesare suspended in air which first must be heated beforethe temperature ofthe oil is raised sufficiently to cause it to vaporize andv ignite.Consequently in open hearth furnaces, part of the mixturedoesnotburn Vcompletely while passing over the .bath and is still burning in the openbrick work in the discharge passage'leading from the furnace. Incompletecombustion results and causes carbonaceous deposits on the open brick orchecker.

work, subjecting it to excessive heat in some places and choking the airpassages in other places.

This incomplete combustion is partially overcome by using higher gradeoils, but such prove expensive in that the oil costs more per unitvolume and contains less heat units per volume than the'low grade oils.

Primarily therefore, an object of my invention is to reduce heatingcosts by providing a method 40 for the eificient combustion of cheap lowgrade oils, while another object of my invention is to obtain a constantand easily controlled heat most efiectively applied.

Another object of my invention is to obtain 4 v 55 parent from thefollowing specification in which these results and eliminate thediificulties herethe illustrative structure shown in the drawings isindicated by the use of reference numerals.

The method contemplated by my invention includes the use of acombustible gas under pressure to atomize the oil and carry it into thecombustion chamber of the furnace. Further, my method includes properlyproportioning, the amounts of oil and gas and controlling the pressuresthereof so that efiicient and complete combustion is made possible. 10

For the purpose of illustration, I shall describe the application of mymethod to heating open hearth furnaces.

In the drawings- Fig. 1 is a top plan view of an open hearth fur- 15nace equipped with oil burning apparatus adapted for carrying out themethod of my invention, the roof being omitted for clearness ofillustration.

Fig. 2 is a partial cross sectional view of the 20 furnace taken on theplane designated by the line 2-2 in Fig. 1.

Fig. 3 is a longitudinal sectional view taken on a plane indicated bythe line 3-3of Fig. 2.

Fig. 4 is a longitudinal sectional view of an oil 25 atornizing gun usedin carrying outv the method of my invention.

Referring to the drawings, l indicates an open hearth furnace of therecuperative reversible type. As illustrated, the furnace has the usual30 I refractory Walls 2 and roof 3 forming a combustion chamber 4, thebottom of which contains a crucible 5 for the metal bath.

Checker work chambers 6 and l communicating with the heating chamberthrough suitable 35 passages such as 8 are provided for preheating theincoming air before it enters the combustion chamber and forrecuperating the heat from the products of combustion as they pass outof the combustion chamber. 40

In operation the combustion chamber is heated alternately from oppositeends, the direction of flow of the air and products of combustionthrough the checker work being correspondingly alternated so that eachchecker work in turn heats the incoming air for an interval and then isheated by the products of combustion.

The furnace is first heated to a temperature sufficient to cause thefuel to ignite as it is introduced thereinto. Liquid fuels, such as oil,are then sprayed into the combustion chamber by suitable oil guns,mounted centrally of the bath in the end walls of the chamber 4,operating alternately as described. These oil guns are preferablyextended over ramps such as 9 and I0,

which slope from the end walls down to the surface of the bath,protecting the guns and causing the burning products'from the guns to bedirected onto the bath surface. They may be mounted so that the flamecan be directed where desired.

For carrying out the method of my invention I find it satisfactory touse an oil gun, such as illustrated in Fig. 4. The gun includes an oilnozzle [2 mounted in a suitable head [3, having a passage l4interconnecting with the nozzle 12. Oil is introduced into the nozzle l2through the passage M from a suitable conduit I5, the amount andpressure of the oil so introduced being regulated by a suitable valve.

Surrounding and spaced from the oil nozzle and extending a shortdistance beyond the discharge end thereof is a gas nozzle I6. Thisnozzle likewise may be carried in the head l3 and communicates with aconduit 11 by means of the passageway 18 in the head. A valve I9 isprovided to regulate the volume and pressure of gas introduced into thenozzle I6. Gas under pressure is supplied to the nozzle I6 from asuitable source such as the compressor 21, capable of supplying thedesired quantity of gas at a pressure of from to pounds per square inch.

A deflector 20, which may be carried by a shaft 2| mounted in the headl3 of the gun is movable axially of the oil nozzle by a screw 22 tocontrol the volume and deflection of the oil stream issuing therefrom.The gas nozzle is contracted at its discharge end 23, so that the gasand oil are commingled and intimately mixed, and the pressure thereoftransformed into velocity as the mixture is driven from the gun.

The gun is protected by a suitable water jacket 24, through which wateris circulated, by introducing it at the front end near the bottomthrough a conduit 25 and discharging it at the top near the rear endthrough a conduit 26.

Experience has proven that the use of relatively expensive fuel orilluminating gas under a pressure of from 40 to 80 pounds and a cheapcrude oil underpressure of from to pounds sprayed from such a gun inproper proportions will heat a furnace efficiently at a cost materiallybelow that heretofore possible.

The pressures and proportions used may be varied, depending upon thequality of gas and oil used and the temperature and the shape of flamedesired. To insure a regular and constant flow of oil and gas, however,the oil pressure should be greater than that of the gas at the orificeof the oil nozzle in the burner. As the mixture 5 passes into the heatedcombustion chamber of the furnace, the gas ignites quickly and burns,adding its heat to the bath and rapidly heating the oil suspendedtherein. Since the oil and gas are in intimate contact, part of the heatof the burning gas completely vaporizes the oil and, aided by a forciblestream of preheated air supplied to the combustion chamber of thefurnace, insures complete combustion of the fuel before it leaves thebath.

In carrying out my process by such an apparatus, I have effected verymarked savings in the cost per ton of reducing steel.

I claim:

1. The method of burning liquid fuel in fur- 20 naces, which includesatomizing the fuel under high pressure by and with a combustible gasunder high pressure at one velocity, transforming the pressure of saidatomized mixture into a higher velocity and directing the mix- 25f tureinto a space heated sufficiently to ignite the gas in the presence ofair, whereby the liquid fuel is quickly vaporized and burned. 1

2. The method of burning oil which includes intimately intermixing theoil under high pressure with an inflammable gas under high pressure atone velocity, transforming said pressures into a higher velocity,directing the mixture to desired points, igniting the gas while the oilis suspended therein and in the presence of air, 35 whereby the oil israpidly transformed into gas, and igniting and burning the resultant gasand air mixture.

3. A method of burning liquid fuel in a furnace, comprising deliveringheavy oil under high 40 pressure into a mixing chamber having acomparatively restricted discharge orifice, delivering inflammable gasunder somewhat lesser pressure into the mixing chamber to mix with andeffectually atomize the oil, discharging the mixture from 45 the mixingchamber first into the presence of heated air and then into a body ofair heated to sufficiently high temperature to cause the gas and oil tobe ignited and burned.

HENRY A. BOST. 50

